Spider Web Diffraction
July 30, 2009
The photo above showing an industrious spider and its opalescent web was captured in my garden in Issy l'Evêque, France. Because of the coloration and the arc-like shape of the web segments, a rainbow may be what comes to mind when observing this phenomenon. However, diffraction and not refraction is responsible for the web’s colors. The thinly spun web is the right diameter to deflect sunlight. The intensity of iridescence in clouds results from minuscule variations in the size of the cloud droplets. With web diffraction, however, color intensity is due to slight variations in the thickness of the web. Photo taken July 2009.
Photo details: EOS 350D Canon camera; f/5-6; ISO 400; 300 mm with Sigma 70-300 DG APO macro lens; speed 1/2000.